The present invention relates to an electrolytic cell for hypochlorite generation.
In line hypochlorination by using sea water or adding sodium chloride, NaCl, to fresh water to chlorinate cooling systems is commonly used in industrial plants and power stations throughout the world. For these systems sodium hypochlorite is derived from the chloride ion in sea or salty water when it is passed through an electrolytic cell or cells. Generally, sodium hypochlorite is produced by hypochlorite generators situated close to the cooling water intake structures of industrial plants and power stations to inject sodium hypochlorite into the cooling water system.
The object for injecting sodium hypochlorite into the industrial water systems is to keep algae and mussel growth from clogging heat exchangers and generator condensers in order to keep plant efficiency at maximum. If heat exchangers and condensers are allowed to build up with algae and mussel growth, the rate of heat exchange becomes inefficient and machinery and equipment can overheat and break down. For this reason it is imperative to keep the cooling water free from any growth that could impede the flow of water in cooling water systems.
In-line sodium hypochlorite generators receive a supply of salty water, either directly from the ocean or from fresh water salted with NaCl generally at a chloride concentration of about 19,000 mg/liter of Clxe2x88x92 and circulate it through an electrolytic cell or cells to provide a sodium hypochlorite solution of up to 2400 mg/liter. Dilute seawater from estuaries or other locations is usable, providing the dilution with fresh water is not excessive and a low concentration of sodium hypochlorite is required.
When salty water is passed between an inert anode and a cathode electrolyzed with a dc voltage, sodium hypochlorite is evolved at the positive anode and gaseous hydrogen at the negative cathode.
In line hypochlorite generators using sea or salty seawater can become inefficient due to calcareous and magnesium deposits on the cathode. While this can be minimized utilizing high flow rates around the electrodes, periodic flush through cleaning must be used to keep the cell generating efficiently. Flushing with dilute hydrochloric acid is employed to clean the cell and maximize the efficiency.
The existing electrolytic cells suffer from a number of disadvantages. Among these disadvantages are inefficiencies due to the cell design and the large physical size of the cell, which means that material costs are high and a heavy support structure is required, together with a greater quantity of copper busbars. This also has the effect that the cost of erection and transport is greater. Further disadvantages exist in that the equipment is generally workshop tested before transport, so it requires the equipment to be dismantled and packed after testing. The dismantling of such cells for inspection purposes is specialized and difficult and requires special tools and equipment. It is also common to require the complete cell to be returned to the vendor for refurbishment.
Other disadvantages exist in that wetted areas other than cathodes or anodes are of exotic metals and that the sodium hypochlorite generator has to be shut down for inspection and replacement of electrodes.
The present invention attempts to overcome at least in part some of the aforementioned disadvantages of previous electrolytic cells for hypochlorite generation.
In accordance with one aspect of the present invention there is provided an electrolytic cell including a plurality of electrodes wherein the electrodes are arranged such that a plurality of channels are defined by adjacent electrodes and each channel is in fluid communication adjacent a first end thereof with a first adjacent channel and is in fluid communication adjacent a second end thereof with a second adjacent channel.